2.2 Evaluating ecosystem services of alpine grassland
Plateau
pika disturbance often produces many
bare soil patches nested in alpine
grasslands (Wilson & Smith, 2015; Yu et al., 2017b; Zhao et al., 2019).
The plot scale was suggested to
better reflect the effects of plateau pika disturbance on plant biomass
and soil properties (Pang et al., 2020a, 2020b) because it can
simultaneously consider the heterogeneity of soil properties in the
presence of plateau pikas and the difference in plant biomass and soil
properties between areas with and without plateau pikas (Pang et al.,
2020b). Therefore, this study used a plot scale to examine plateau pika
disturbance and its disturbance intensity in relation to forage
availability, water conservation, carbon sequestration and soil nutrient
maintenance services and used a quadrat scale to examine plateau pika
disturbance and its disturbance intensity in relation to the
biodiversity conservation service.
Although there were many kinds of
bare soil patches in the alpine grasslands, this study was restricted to
the bare soil patches induced by plateau pikas. In the presence of
plateau pikas, the soil water storage, soil organic carbon, soil total
nitrogen, phosphorus and potassium stocks were calculated in the bare
soil surface and vegetated surface,
respectively.
In this study, the forage
availability service was estimated by palatable plant biomass
(Martínez-Estévez et al., 2013).
The biodiversity conservation service was estimated by plant species
richness (Wen et al., 2013). Water conservation services can be assessed
by soil water storage (Ouyang et al., 2011). The carbon sequestration
service can be evaluated by the soil organic carbon stock (Wen et al.,
2013). Soil nutrient maintenance services can be assessed by soil total
nitrogen, phosphorus, and potassium stocks (Wen et al, 2013).